Captjetblast From Argentina, joined Aug 2001, 280 posts, RR: 0 Reply 1, posted (12 years 1 month 1 week 15 hours ago) and read 881 times:
Maybe a pilot or engineer will give a better explanation on what yaw dampers are, but based on Flight Simulator, I understand it's useful when flying at high altitudes and speeds, preventing the plane from oscillating up and down.
Please anyone feel free to make any necessary correction to my post.
Seagull From United States of America, joined Jun 2001, 340 posts, RR: 1 Reply 2, posted (12 years 1 month 1 week 14 hours ago) and read 865 times:
Yes, many of us know what a "yaw damper is", and the above post is partially correct in that it's useful at high altitudes and speeds. You will not get much useful response in this section, I'm afraid, restate your question more clearly and post it in the tech section.
Aerokid From Belgium, joined Jun 2000, 348 posts, RR: 1 Reply 5, posted (12 years 1 month 1 week 13 hours ago) and read 844 times:
A yaw damper is used to prevent the aircraft from going into a dutch roll.
If, for some reason (wind gust for example), the aircraft slips (i.e. it turns without rolling: the aircraft's nose doesn't point to the direction of flight anymore), then, because of that turn the speed of the airfoil around the wings is not the same anymore (for a short while). One wing will generate more lift than the other and the aircraft starts rolling. At the same time (when the aircraft is turning) the entire vertical stabilizer catches wind, forcing the aircraft in a turn in the other direction.
The aircraft will of course not stop turning at exactly zero degrees yaw, it will go a bit further and the other side of the vertical stabilizer will start catching wind, the other wing will start generating more lift... The process starts all over again and this, COMBINED with the pilot's corrective actions could result in a uncontrollable situation. This is also commonly referred to as "pilot induced oscillations".
What a Yaw damper consists of physically, I don't know. I guess it is some electronic control unit (in the case of Airbus FBW certainly) that limits the deflection of the rudder. Maybe there's a hydromechanical coupling as well.
I know it might sound complicated, it is just not easy to explain (and understand) without the aid of a figure or drawing.